Peppered moth evolution - AbsoluteAstronomy.com

The evolution of the peppered moth
Peppered moth
The peppered moth is a temperate species of night-flying moth. Peppered moth evolution is often used by educators as an example of natural selection.- Distribution :...

over the last two hundred years has been studied in detail. Originally, the vast majority of peppered moths had light colouration, which effectively camouflage

Camouflage

Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...

d them against the light-coloured trees and lichens which they rested upon. However, because of widespread pollution during the Industrial Revolution

Industrial Revolution

The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

in England, many of the lichens died out, and the trees that peppered moths rested on became blackened by soot

Soot

Soot is a general term that refers to impure carbon particles resulting from the incomplete combustion of a hydrocarbon. It is more properly restricted to the product of the gas-phase combustion process but is commonly extended to include the residual pyrolyzed fuel particles such as cenospheres,...

, causing most of the light-coloured moths, or typica, to die off from predation. At the same time, the dark-coloured, or melanic, moths, carbonaria, flourished because of their ability to hide on the darkened trees.

Since then, with improved environmental standards, light-coloured peppered moths have again become common, but the dramatic change in the peppered moth's population has remained a subject of much interest and study, and has led to the coining of the term industrial melanism
Melanism
Melanism is an undue development of dark-colored pigment in the skin or its appendages, and the opposite of albinism. It is also the medical term for black jaundice.The word is deduced from the , meaning black pigment....

to refer to the genetic darkening of species in response to pollutants. As a result of the relatively simple and easy-to-understand circumstances of the adaptation, the peppered moth has become a common example used in explaining or demonstrating natural selection

Natural selection

Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....

Genetics

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

is defined as "a change in the frequency of an allele

Allele

An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...

within a gene pool

Gene pool

In population genetics, a gene pool is the complete set of unique alleles in a species or population.- Description :A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection...

", an occurrence that causes a population

Population genetics

Population genetics is the study of allele frequency distribution and change under the influence of the four main evolutionary processes: natural selection, genetic drift, mutation and gene flow. It also takes into account the factors of recombination, population subdivision and population...

's genetically inherited traits

Trait (biology)

A trait is a distinct variant of a phenotypic character of an organism that may be inherited, environmentally determined or be a combination of the two...

to change over successive generations. Evolution in the wild is chiefly caused by two mechanisms: natural selection

Natural selection

, the process by which individual organisms with beneficial traits are more likely to survive and reproduce, and genetic drift

Genetic drift

Genetic drift or allelic drift is the change in the frequency of a gene variant in a population due to random sampling.The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces...

, the statistical drift over time of allele frequencies

Allele frequency

Allele frequency or Gene frequency is the proportion of all copies of a gene that is made up of a particular gene variant . In other words, it is the number of copies of a particular allele divided by the number of copies of all alleles at the genetic place in a population. It can be expressed for...

in a population from random sampling effects in the formation of successive generations.

J.W. Tutt first proposed the "differential bird predation hypothesis" in 1896, as a mechanism of natural selection. The melanic morphs were better camouflaged against the bark of trees without foliose lichen, whereas the typica morphs were better camouflaged against trees with lichens. As a result, birds would find and eat those morphs that were not camouflaged with increased frequency.

In 1924, J.B.S. Haldane calculated, using a simple general selection model

General selection model

The General Selection Model is a model of population genetics that describes how a population's genotype will change when acted upon by natural selection.-Equation:The General Selection Model is encapsulated by the equation:...

, the selective advantage necessary for the recorded evolution of peppered moths, based on the assumption that in 1848 the frequency of dark-coloured moths was 2%, and by 1895 it was 95%. The dark-coloured, or melanic, form would have had to be one and a half times as fit as the typical, light-coloured form. Even taking into consideration the errors in the model, this reasonably excluded the stochastic

Stochastic

Stochastic refers to systems whose behaviour is intrinsically non-deterministic. A stochastic process is one whose behavior is non-deterministic, in that a system's subsequent state is determined both by the process's predictable actions and by a random element. However, according to M. Kac and E...

process of genetic drift, because the changes were too fast.

In peppered moths, the allele for dark-bodied moths is dominant, while the allele for light-bodied moths is recessive, meaning that the typica moths have a phenotype

Phenotype

A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...

(visible or detectable characteristic) that is only seen in a homozygous genotype

Genotype

The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...

(an organism that has two copies of the same allele), and never in a heterozygous one. This helps explain how dramatically quickly the population changed when being selected

Selection

In the context of evolution, certain traits or alleles of genes segregating within a population may be subject to selection. Under selection, individuals with advantageous or "adaptive" traits tend to be more successful than their peers reproductively—meaning they contribute more offspring to the...

for dark colouration.

The peppered moth Biston betularia is also a model of parallel evolution

Parallel evolution

Parallel evolution is the development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades.-Parallel vs...

in the incidence of melanism in the British form (f. carbonaria) and the American form (f. swettaria) as they are indistinguishable in appearance. Genetic analysis indicates that both phenotypes are inherited as autosomal dominants. Cross hybridizations indicate the phenotypes are produced by isoalleles at a single locus.

Environmental changes

Before the Industrial Revolution

Industrial Revolution

, the peppered moth was mostly found in a light grey form with little black speckled spots. The light-bodied moths were able to blend in with the light-coloured lichens and tree bark, and the less common black moth was more likely to be eaten by birds. As a result of the common light-coloured lichens and English trees, therefore, the light-coloured moths were much more effective at hiding from predators, and the frequency of the dark allele was about 0.01%.

During the early decades of the Industrial Revolution in England, the countryside between London and Manchester was blanketed with soot

Soot

from the new coal-burning factories. Many of the light-bodied lichens died from sulphur dioxide

Sulfur dioxide

Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...

emissions, and the trees became covered with soot. This led to an increase in bird predation for light-coloured moths, as they no longer blended in as well in their polluted

Air pollution

Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere....

ecosystem

Ecosystem

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

: indeed, their bodies now dramatically contrasted with the colour of the bark. Dark-coloured moths, on the other hand, were camouflage

Camouflage

d very well by the blackened trees.

Although a majority of light-coloured moths initially continued to be produced, most of them didn't survive, while the dark-coloured moths flourished. As a result, over the course of many generations of moths, the allele frequency gradually shifted towards the dominant allele, as more and more dark-bodied moths survived to reproduce. By the mid-19th century, the number of dark-coloured moths had risen noticeably, and by 1895, the percentage of dark-coloured moths in the Manchester peppered moth population was reported at 98%, a dramatic change (by almost 1000%) from the original frequency. This evolved darkening in colour as a result of industrialization has come to be known as industrial melanism
Melanism
Melanism is an undue development of dark-colored pigment in the skin or its appendages, and the opposite of albinism. It is also the medical term for black jaundice.The word is deduced from the , meaning black pigment....

as a result.

While evidence of increasing frequency of melanic forms in the Lepidoptera was available during Darwin’s lifetime – the first observations were made in 1848 – current understanding is that it was not until 1896, 14 years after Darwin’s death, that Tutt explicitly linked melanism with natural selection. However, a recent article reports that melanism in the Lepidoptera had been linked to natural selection prior to Tutt. Albert Brydges Farn (1841–1921), a British entomologist, wrote to Darwin on the 18th November 1878 to discuss his observation of colour variations in the Annulet moth (then Gnophos obscurata, now Charissa obscurata). In his letter, Farn mentions the existence of different colour morphs, describing how each is matched to the habitats in which they are found (dark morphs on peat, white morphs on chalk cliffs) and refers explicitly to this variability as pointing to ‘survival of the fittest’.

In modern times, because of cleaner air standards in Europe and North America, the dark-bodied moth is becoming less frequent, again demonstrating the adaptive

Adaptation

An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....

shifts in the peppered moth population.

Rise and fall of phenotype frequency

Melanism

Melanism is an undue development of dark-colored pigment in the skin or its appendages, and the opposite of albinism. It is also the medical term for black jaundice.The word is deduced from the , meaning black pigment....

has appeared in the European and North American peppered moth populations. Information about the rise in frequency is scarce. Much more is known about the subsequent fall in phenotype frequency, as it has been measured by lepidopterist

Lepidopterist

A lepidopterist is a person who specialises in the study of Lepidoptera, members of an order encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...

s using moth traps.

Though a black peppered moth was found in 1811, this can be seen as an aberrant morph caused by a recurrent mutation that was probably selected out of the population. The first carbonaria to be found was caught in Manchester

Manchester

Manchester is a city and metropolitan borough in Greater Manchester, England. According to the Office for National Statistics, the 2010 mid-year population estimate for Manchester was 498,800. Manchester lies within one of the UK's largest metropolitan areas, the metropolitan county of Greater...

, England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

in 1848, but was only reported 16 years later in 1864 by Edleston. Edleston notes that by 1864 it was the more common morph in his garden in Manchester. Steward compiled data for the first recordings of the peppered moth by locality, and deduced that the carbonaria morph was the result of a single mutation

Mutation

In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...

that subsequently spread. By 1895, it had reached a reported frequency of 98% in Manchester.

From around 1962 to the present, the phenotype frequency of carbonaria has steadily fallen. Its decline has been measured more accurately than its rise, because of more rigorous scientific studies being conducted. Notably, Bernard Kettlewell conducted a national survey in 1956, Bruce Grant conducted a similar one in early 1996.
, and L.M. Cook in 2003.

Similar results were found in America. Melanic forms have not been found in Japan. It is believed that this is because peppered moths in Japan do not inhabit industrialised regions.

Predation experiments

In 1896 J. W. Tutt

J. W. Tutt

James William Tutt was an English entomologist.Tutt was the author of The British Noctuae and their Varieties ,Natural History of the British Lepidoptera and "Practical hints for the Field lepidopterist" ....

hypothesised that the increased proportion of carbonaria resulted from differential bird predation

Predation

In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...

giving an advantage to the melanistic phenotype in polluted regions, but not in unpolluted regions where the light coloured typica moths had the advantage. Various experiments have been performed on predation of the peppered moth and each has supported this hypothesis.

The most famous experiments on the peppered moth were carried out by Bernard Kettlewell

Bernard Kettlewell

Henry Bernard Davis Kettlewell was a British geneticist, lepidopterist and medical doctor, who carried out research into the influence of industrial melanism on natural selection in moths, showing why moths are darker in polluted areas.-Early life:Kettlewell was born in Howden, Yorkshire, and...

under the supervision of E. B. Ford, who helped him gain a grant from the Nuffield Foundation

Nuffield Foundation

The Nuffield Foundation is a British charitable trust, established in 1943 by William Morris , the founder of the Morris Motor Company. Lord Nuffield wanted to contribute to improvements in society, including the expansion of education and the alleviation of disadvantage...

to perform the experiments. In one of Kettlewell's experiment

Kettlewell's experiment

In Great Britain during the late 1840s through the 1850s, it was noticed that there was a reduced number of light colored European peppered moths and an increased number of the darker colored moths in the industrial areas...

s, moths were released into a large (18 m by 6 m) aviary, where they were fed on by Great Tit

Great Tit

The Great Tit is a passerine bird in the tit family Paridae. It is a widespread and common species throughout Europe, the Middle East, Central and Northern Asia, and parts of North Africa in any sort of woodland. It is generally resident, and most Great Tits do not migrate except in extremely...

s (Parus major). In 1953, Kettlewell experimented at Cadbury Nature Reserve in Birmingham

Birmingham

Birmingham is a city and metropolitan borough in the West Midlands of England. It is the most populous British city outside the capital London, with a population of 1,036,900 , and lies at the heart of the West Midlands conurbation, the second most populous urban area in the United Kingdom with a...

, England

England

, marking, releasing and recapturing marked moths. He found that in this polluted woodland typica morphs were preferentially preyed. He thus showed that the melanistic phenotype was important to the survival of peppered moths in such a habitat. Kettlewell repeated the experiment in 1955 at unpolluted woodland in Dorset

Dorset

Dorset , is a county in South West England on the English Channel coast. The county town is Dorchester which is situated in the south. The Hampshire towns of Bournemouth and Christchurch joined the county with the reorganisation of local government in 1974...

and again in the polluted woods in Birmingham. He was accompanied by Nico Tinbergen, and they made a film together. Further studies by others found similar results, culminating in 1996 when reporting work on both sides of the Atlantic found a correlation between changes in melanic frequencies and pollution levels.

An experiment in field biology will always suffer from some level of artificiality, but that has to be balanced against practicality, costs and in this case the history of field biology; the most important aspect is that an experiment generates useful statistics. The only previous experiments of this type were R.A. Fisher

Ronald Fisher

Sir Ronald Aylmer Fisher FRS was an English statistician, evolutionary biologist, eugenicist and geneticist. Among other things, Fisher is well known for his contributions to statistics by creating Fisher's exact test and Fisher's equation...

and E.B. Ford

E.B. Ford

Edmund Brisco "Henry" Ford FRS Hon. FRCP was a British ecological geneticist. He was a leader among those British biologists who investigated the role of natural selection in nature. As a schoolboy Ford became interested in lepidoptera, the group of insects which includes butterflies and moths...

's (1947) with the scarlet tiger moth

Scarlet tiger moth

The Scarlet Tiger Moth is a colorful moth of Europe, Turkey, Transcaucasus, northern Iran. It belongs to the tiger moth family, Arctiidae....

.

Michael Majerus

Michael Majerus

Michael Eugene Nicolas Majerus was a geneticist and Professor of Ecology at Clare College, Cambridge, an enthusiast who became a world authority in his field of evolutionary biology. He was widely noted for his work on moths and ladybirds and as an advocate of the science of evolution...

in his 1998 book Melanism: Evolution in Action
Melanism: Evolution in Action
thumb|220px|Melanism in ActionMelanism: Evolution in Action is a book by Dr Mike Majerus, published in 1998. It is an update of Bernard Kettlewell's book The Evolution of Melanism....

discussed criticisms concerning Kettlewell's experimental methods. Criticism and controversy arose when the book was misrepresented in reviews, and the story was picked up by creationist

Creationism

Creationism is the religious beliefthat humanity, life, the Earth, and the universe are the creation of a supernatural being, most often referring to the Abrahamic god. As science developed from the 18th century onwards, various views developed which aimed to reconcile science with the Genesis...

campaigners. The journalist Judith Hooper

Judith Hooper

Judith Hooper is an American journalist.Hooper has worked as an editor and writer for the magazine Omni. With her husband, Dick Teresi, she co-wrote the books The Three-Pound Universe and Would the Buddha Wear a Walkman? A Catalogue of Revolutionary Tools for Higher Consciousness...

suggested in her book Of Moths and Men
Of Moths and Men
Of Moths and Men is a controversial book by the journalist Judith Hooper about the Oxford University ecological genetics school led by E.B. Ford. The book specifically concerns Bernard Kettlewell's experiments on the peppered moth which were intended as experimental validation of evolution...

(2002) that Kettlewell committed scientific fraud

Fraud

In criminal law, a fraud is an intentional deception made for personal gain or to damage another individual; the related adjective is fraudulent. The specific legal definition varies by legal jurisdiction. Fraud is a crime, and also a civil law violation...

. Careful studies of Kettlewell's surviving papers by Rudge (2005) and Young (2004) have revealed that Hooper's allegation of fraud is unjustified, and "that Hooper does not provide one shred of evidence to support this serious allegation”.

In 2000 Majerus developed plans for experiments to establish where peppered moths rest through the day, and to examine if the various valid criticisms of Kettlewell’s experimental protocols could have altered the qualitative validity of his conclusions. In the following year he piloted a new field predation experiment designed to overcome criticisms that Kettlewell had used too few release sites, resulting in the density of moths being too high; moths had been released onto tree trunks rather than branches; moths released during the day might not have found the best places to hide; mixtures of wild-caught and lab-bred moths might have behaved differently; and the behaviour of translocated moths might have changed because of local adaptation. During the main experiment in Cambridge

Cambridge

The city of Cambridge is a university town and the administrative centre of the county of Cambridgeshire, England. It lies in East Anglia about north of London. Cambridge is at the heart of the high-technology centre known as Silicon Fen – a play on Silicon Valley and the fens surrounding the...

over the seven years 2001-2007 Majerus noted the natural resting positions of the moths, and of the 135 moths examined over half were on tree branches, mostly on the lower half of the branch, 37% were on tree trunks, mostly on the north side, and only 12.6% were resting on or under twigs. Following correspondence with Hooper he added an experiment to find if bat

Bat

Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...

predation might have skewed the results – this found that bats preyed equally on both forms of the moth. He observed a number of species of bird preying on the moths, and the overall data led him to conclude that differential bird predation was a major factor responsible for the decline in carbonaria frequency compared to typica in Cambridge during the study period. He described his results as a complete vindication of the peppered moth story, and said "If the rise and fall of the peppered moth is one of the most visually impacting and easily understood examples of Darwinian evolution in action, it should be taught. It provides after all the proof of evolution."

Alternative hypotheses

Several alternative hypotheses to explain industrial melanism

Melanism

, particularly noted in the peppered moth, were proposed during the 1920s and 1930s. Some dissenters within the scientific community have criticized the peppered moth story, notably Sargent et al. (1998), but peppered moth researchers remain unconvinced.

Several alternative selection mechanisms have been proposed. Note that a change in allele frequency

Allele frequency

, be it caused by natural selection

Natural selection

, mutation

Mutation

, migration or genetic drift

Genetic drift

by definition, is differential

Cellular differentiation

In developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type. Differentiation occurs numerous times during the development of a multicellular organism as the organism changes from a simple zygote to a complex system of...

. However, the magnitude of the changes observed can only be accounted for by natural selection. It can be seen from population genetics

Population genetics

that a non-differential change will not cause evolution. If the allele frequencies are denoted by the algebra

Algebra

Algebra is the branch of mathematics concerning the study of the rules of operations and relations, and the constructions and concepts arising from them, including terms, polynomials, equations and algebraic structures...

ic terms p and q, and (say) p = 0.6 and q = 0.4, then a non-differential reduction in population size from say 2000 to 100 individuals, will still produce the same values of (approximately) p = 0.6 and q = 0.4.

Phenotypic induction

John William Heslop-Harrison

John William Heslop Harrison, FRS, , was Professor of Botany at King's College, Durham , now perhaps best remembered for an alleged academic fraud....

(1920) rejected Tutt's differential bird predation hypothesis, on the basis that he did not believe that birds ate moths. Instead he advocated the idea that pollutants could cause changes to the soma and germ plasm of the organism.
The origin of this hypothesis probably has its roots in the 1890s, when it was proposed as a form of Lamarckism

Lamarckism

Lamarckism is the idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring . It is named after the French biologist Jean-Baptiste Lamarck , who incorporated the action of soft inheritance into his evolutionary theories...

. It is important to note its historical context.

Hasebroek (1925) was the first who tried to prove this hypothesis, he contended that air pollution altered lepidopteran physiology, thus producing an excess of black pigment. He exposed pupae of Lepidoptera to various doses of pollutant gases, namely hydrogen sulfide

Hydrogen sulfide

Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...

(H₂S), ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

(NH₃) and "pyredin" (presumably his spelling of pyridine

Pyridine

Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...

). He used eight species in his studies, four of which were species of butterfly that did not exhibit melanism. Ford (1964) contends that Hasebroek's illustrations showed that the abnormal forms that appeared were not melanics, and Hasebroek failed to study their genetics.

Heslop Harrison

John William Heslop-Harrison

John William Heslop Harrison, FRS, , was Professor of Botany at King's College, Durham , now perhaps best remembered for an alleged academic fraud....

(Harrison and Garrett 1926; Harrison 1928) suggested that the increase of melanic moths in industrialised regions was due to "mutation pressure", not to selection by predators which he regarded as negligible. Salts of lead

Lead

Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

and manganese

Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

were present in the airborne pollutant particles, and he suggested that these caused the mutation of genes for melanin production but of no others. He used Selenia bilunaria and Tephrosia bistortata as material. The larvae were fed with leaves that had incorporated these salts and melanics subsequently appeared.

Similar experiments by Hughes McKenney (1932) and Thomasen and Lemche (1933) failed to replicate these results. However, the statistician and geneticist Ronald Fisher

Ronald Fisher

, showed that Heslop Harrison's controls were inadequate. This hypothesis, however, appeared to be falsified by breeding experiments. Further evidence, if it were needed, is likely to come from research into the biochemistry of melanism.

Criticism

The use of the peppered moth as an example of evolution has come under attack by creationists

Creationism

, including advocates of intelligent design

Intelligent design

Intelligent design is the proposition that "certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection." It is a form of creationism and a contemporary adaptation of the traditional teleological argument for...

, who allege that it is not reliable as evidence of evolution

Evidence of evolution

of living things has been discovered by scientists working in a variety of fields over many years. This evidence has demonstrated and verified the occurrence of evolution and provided a wealth of information on the natural processes by which the variety and diversity of life on Earth developed...

. Creationists have argued that the "peppered moth story" showed only microevolution

Microevolution

Microevolution is the changes in allele frequencies that occur over time within a population. This change is due to four different processes: mutation, selection , gene flow, and genetic drift....

, rather than speciation

Speciation

Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...

or other changes at the larger macroevolution

Macroevolution

Macroevolution is evolution on a scale of separated gene pools. Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes within a species or population.The process of speciation may fall...

ary scale. Biologists agree that this example shows natural selection causing evolution within a species, demonstrating rapid and obvious adaptiveness with such change, and accept that it is not proof of the theory of evolution as a whole. Although creationists accept microevolution of varieties within a kind, they claim that macroevolution does not happen. To biologists there is no dividing line between the two, and in the modern evolutionary synthesis

Modern evolutionary synthesis

The modern evolutionary synthesis is a union of ideas from several biological specialties which provides a widely accepted account of evolution...

the same mechanisms are seen operating at various scales to cause both evolution within species and speciation at a macroevolution level or wider changes, the only difference being of time and scale.

Another common creationist criticism involves well-known pictures of moths resting on trunks that are used in many textbooks. These photos were prepared (dead moths pinned to branches), which has been conflated into the idea that all the studies were staged. Professional photography to illustrate textbooks uses dead insects because of the considerable difficulty in getting good images of small, relatively fast moving animals. The studies actually consisted of observational data rather than using such photographs. The photographs in Michael Majerus

Michael Majerus

's 1998 book Melanism: Evolution in Action
Melanism: Evolution in Action
thumb|220px|Melanism in ActionMelanism: Evolution in Action is a book by Dr Mike Majerus, published in 1998. It is an update of Bernard Kettlewell's book The Evolution of Melanism....

are unstaged pictures of live moths in the wild, and the photographs of moths on tree-trunks, apart from some slight blurring, look no different than the "staged" photographs. While an experiment did involve the gluing of dead moths to trees, this practice was just one of many different ways used to study different individual elements of the overall hypothesis. This particular experiment was not meant to exactly reproduce natural conditions but instead was used to assess how the numbers of moths available (their density) affected the foraging practices of birds.

The methodology of Bernard Kettlewell

Bernard Kettlewell

's classic study was questioned by the biologist Jerry Coyne

Jerry Coyne

-Online articles:* , The New Republic* , The New Republic* , The New Republic* ", The New Republic * -Online articles:* , The New Republic* , The New Republic* , The New Republic* ", The New Republic (Review of Michael Behe's The Edge of Evolution)* -Online articles:* , The New Republic* , The...

in Nature in a review of Michael Majerus's 1998 book Melanism: Evolution in Action which includes a critique of Kettlewell's experiment

Kettlewell's experiment

, matching a similar 1998 analysis by Sargent et al. Coyne stated that the most serious problem found by Majerus was that only two peppered moths had been found on tree trunks. He also wrote that the white moths had increased in numbers before the lichen had returned and that Kettlewell's findings of moths choosing matching backgrounds had not been replicated in later experiments. Coyne compared his reaction to "the dismay attending my discovery, at the age of 6, that it was my father and not Santa who brought the presents on Christmas Eve". He concluded that "for the time being we must discard Biston as a well-understood example of natural selection in action, although it is clearly a case of evolution. There are many studies more appropriate for use in the classroom" and that further studies of the animal's habits were needed. At the beginning of his second paragraph on the peppered moths, Majerus emphasizes that the wealth of additional data obtained since Kettlewell's initial predation papers does not undermine the basic qualitative deductions from that work and that differential bird predation of the dark and light moths in habitats affected by industrial pollution to different degrees (directional selection

Directional selection

In population genetics, directional selection is a mode of natural selection in which a single phenotype is favored, causing the allele frequency to continuously shift in one direction...

) "is the primary influence of the evolution of melanism in the peppered moth". Coyne had erred in his statement that only two peppered moths had been found on tree trunks, as the book gives the resting positions of 47 peppered moths Majerus had found in the wild between 1964 and 1996; twelve were on tree trunks (six exposed, six unexposed), twenty were at the trunk/branch joint, and fifteen resting on branches. Majerus found that the review did not reflect the factual content of the book or his own views, and cites an assessment by the entomologist

Entomology

Entomology is the scientific study of insects, a branch of arthropodology...

Donald Frack that there was essentially no resemblance between the book and Coyne's review, which appeared to be a summary of the Sargent et al. paper rather than Majerus's book.

The review was subsequently picked up by journalist Robert Matthews, who wrote an article for The Sunday Telegraph
Sunday Telegraph
The Sunday Telegraph is a British broadsheet newspaper, founded in February 1961. It is the sister paper of The Daily Telegraph, but is run separately with a different editorial staff, although there is some cross-usage of stories...

, March 14th, 1999, claiming that "Evolution experts are quietly admitting that one of their most cherished examples of Darwin's theory, the rise and fall of the peppered moth, is based on a series of scientific blunders. Experiments using the moth in the Fifties and long believed to prove the truth of natural selection are now thought to be worthless, having been designed to come up with the 'right' answer". Majerus regarded this view as surprising, and not one that would be shared by those involved in the field. He noted numerous scientific inaccuracies, misquotations and misrepresentations in the article, but thought this was common in press reports. He stated that he had spoken to Matthews for over half an hour and had to explain many details as Matthews hadn't read the book, but "Even then, he got nearly everything wrong."

The story was taken up by creationists, and at a seminar presenting the wedge strategy

Wedge strategy

The wedge strategy is a political and social action plan authored by the Discovery Institute, the hub of the intelligent design movement. The strategy was put forth in a Discovery Institute manifesto known as the Wedge Document, which describes a broad social, political, and academic agenda whose...

on March 13th, 1999, the leading intelligent design proponent Phillip E. Johnson

Phillip E. Johnson

Phillip E. Johnson is a retired UC Berkeley law professor and author. He became a born-again Christian while a tenured professor and is considered the father of the intelligent design movement...

said that the moths "do not sit on tree trunks", "moths had to be glued to the trunks" for pictures and that the experiments were "fraudulent" and a "scam." This led Frack to exchanges with intelligent design proponent Jonathan Wells, who conceded that Majerus listed six moths on exposed tree trunks (out of 47), but argued that this was "an insignificant proportion". Wells wrote an essay on the subject, a shortened version of which appeared in The Scientist
The Scientist
The Scientist: Magazine of Life Sciences is a professional magazine intended for life scientists. Coverage includes reviews of widely noticed research papers, informing its audience of current research, updates to technology, updates to career information, profiles of scientists achieving...

of May 24th, 1999, claiming that "In 25 years of fieldwork, C.A. Clarke and his colleagues found only one peppered moth on a tree trunk", and concluding that "The fact that peppered moths do not normally rest on tree trunks invalidates Kettlewell's experiments". In 2000 he wrote Icons of Evolution
Icons of Evolution
Icons of Evolution is a book by the intelligent design advocate and fellow of the Discovery Institute, Jonathan Wells, which also includes a 2002 video companion. In the book, Wells criticized the paradigm of evolution by attacking how it is taught...

: Why much of what we Teach About Evolution is Wrong, which claims "What the textbooks don't explain, however, is that biologists have known since the 1980s that the classical story has some serious flaws. The most serious is that peppered moths in the wild don't even rest on tree trunks. The textbook photographs, it turns out, have been staged." The arguments put by Wells have been dismissed by Majerus, Cook and peppered moth researcher Bruce Grant

Bruce Grant

Professor Bruce S. Grant is emeritus professor of biology at the College of William and Mary. He has a particular research interest in the peppered moth. He is a defender of the teaching of evolution and has criticized creationist Jonathan Wells, who has cited his work, as "dishonest."Grant has a...

who describes Wells as distorting the picture by selectively omitting or scrambling references in a way that is dishonest.

On November 27th, 2000, the school board of Pratt County, Kansas

Pratt County, Kansas

Pratt County is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 9,656. The largest city and county seat is Pratt.-19th century:...

continued efforts to favor intelligent design teaching by requiring the use of specific resources. These included the article by Jerry Coyne, who wrote to object strongly to this creationist misrepresentation of his critical re-evaluation, emphasising that the moth story is a sound example of evolution produced by natural selection and stating that his call for additional research was only to resolve uncertainty regarding bird predation as the cause of the natural selection and evolutionary change. Bruce Grant also wrote to challenge allegations of fraud in the moth experiments based on misrepresentations by Wells. In 2002, Judith Hooper's Of Moths and Men
Of Moths and Men
Of Moths and Men is a controversial book by the journalist Judith Hooper about the Oxford University ecological genetics school led by E.B. Ford. The book specifically concerns Bernard Kettlewell's experiments on the peppered moth which were intended as experimental validation of evolution...

added to the accusations of scientific fraud. She accused Kettlewell of manipulating his data to prove his hypothesis. The book received strong criticism from the scientific press (e.g., Coyne, B.C. Clarke, Grant). Majerus described it as "littered with errors, misrepresentations, misinterpretations and falsehoods".

External links

Bruce Grant
Bruce Grant
Professor Bruce S. Grant is emeritus professor of biology at the College of William and Mary. He has a particular research interest in the peppered moth. He is a defender of the teaching of evolution and has criticized creationist Jonathan Wells, who has cited his work, as "dishonest."Grant has a...

has written several papers on melanism in the peppered moth which are listed on his home page.
Online lecture: "The rise and fall of the melanic Peppered Moth" presented by Laurence Cook.
The Peppered Moth: Decline of a Darwinian Disciple. This is the transcript of Michael Majerus
Michael Majerus
Michael Eugene Nicolas Majerus was a geneticist and Professor of Ecology at Clare College, Cambridge, an enthusiast who became a world authority in his field of evolutionary biology. He was widely noted for his work on moths and ladybirds and as an advocate of the science of evolution...

' lecture delivered to the British Humanist Association
British Humanist Association
The British Humanist Association is an organisation of the United Kingdom which promotes Humanism and represents "people who seek to live good lives without religious or superstitious beliefs." The BHA is committed to secularism, human rights, democracy, egalitarianism and mutual respect...

on Darwin Day
Darwin Day
Darwin Day is a recently instituted celebration intended to commemorate the anniversary of the birth of Charles Darwin on February 12, 1809. The day is used to highlight Darwin's contribution to science and to promote science in general.-History:...

2004.
The Peppered Moth: The Proof of Darwinian Evolution. This is the transcript of Majerus' lecture given at the European Society for Evolutionary Biology
European Society for Evolutionary Biology
The European Society for Evolutionary Biology was founded in 1987. It is publishing the Journal of Evolutionary Biology, organises meetings and biannually awards a John Maynard Smith Prize.As of 2007 its president is Isabelle Olivieri....

meeting on 23 August 2007. The accompanying powerpoint presentation is also available.
On 19 June 2009, Telegraph.co.uk published an article on this evolutionary phenomenon and implored UK readers to visit the Moths Count website and record their observations of local moths, in an effort to help increase the available data for researchers.

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